When a robot is hit by ammo with IRRADIATED component,
it damages allied robots near him (with a nice uranium glow for instance).
So, it is necessary to isolate him from other mechs
hence decreasing concentration of firing power of the squad.
But this bot can fire.
I think, for the battle ground,we can plague a zone with this glow too,
preventing mechs to stay here.
Or with moving clouds of dangerous substances damaging or blocking or twisting abilities.
With the components I wrote about in another post we can plague a zone too: rust, etc...
At high levels, we can imagine lead shields (like lead pigs) to limit damages of radioactivity
but not eliminate them.